Browsing by Author "Engels, D."

Now showing items 1-10 of 10

    • Investigating the Unification of LOFAR-detected powerful AGN in the Boötes Field 

      Morabito, Leah K.; Williams, W. L.; Duncan, Kenneth J.; Röttgering, H.~J.~A.; Miley, George; Saxena, Aayush; Barthel, Peter; Best, Philip N.; Bruggen, M.; Brunetti, G.; Chyży, K. T.; Engels, D.; Hardcastle, M. J.; Harwood, J. J.; Jarvis, Matt J.; Mahony, E. K.; Prandoni, I.; Shimwell, Timothy W.; Shulevski, Alexander; Tasse, C. (2017-08-01)
      Low radio frequency surveys are important for testing unified models of radio-loud quasars and radio galaxies. Intrinsically similar sources that are randomly oriented on the sky will have different projected linear sizes. ...

    • LOFAR 150-MHz observations of the Boötes field: Catalogue and Source Counts 

      Williams, W. L.; Van Weeren, R. J.; Röttgering, H. J. A.; Best, P.; Dijkema, T. J.; Gasperin, F. de; Hardcastle, M. J.; Heald, G.; Prandoni, I.; Sabater, J.; Shimwell, T. W.; Tasse, C.; Bemmel, I. M. van; Brüggen, M.; Brunetti, G.; Conway, J. E.; Enßlin, T.; Engels, D.; Falcke, H.; Ferrari, C.; Haverkorn, M.; Jackson, N.; Jarvis, M. J.; Kapinska, A. D.; Mahony, E. K.; Miley, G. K.; Morabito, L. K.; Morganti, R.; Orrú, E.; Retana-Montenegro, E.; Sridhar, S. S.; Toribio, M. C.; White, G. J.; Wise, M. W.; Zwart, J. T. L. (2016-08-11)
      We present the first wide area (19 deg$^2$), deep ($\approx120-150$ {\mu}Jy beam$^{-1}$), high resolution ($5.6 \times 7.4$ arcsec) LOFAR High Band Antenna image of the Bo\"otes field made at 130-169 MHz. This image is at ...

    • LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra 

      McKean, J. P.; Godfrey, L. E H; Vegetti, S.; Wise, Michael W.; Morganti, R.; Hardcastle, M. J.; Rafferty, D.; Avruch, I. M.; Beck, R.; Bell, M. E.; Bemmel, I. M. van; Bentum, M. J.; Bernardi, G.; Best, Philip; Blaauw, R.; Bonafede, A.; Breitling, F.; Broderick, J. W.; Brüggen, Marcus; Cerrigone, L.; Ciardi, B.; De Gasperin, Francesco; Deller, A.; Duscha, S.; Engels, D.; Falcke, H.; Fallows, R. A.; Frieswijk, W.; Garrett, M.A.; Grießmeier, J. -M.; Haarlem, M. P. van; Heald, G.; Hoeft, Matthias; van der, HorstA J.; Iacobelli, M.; Interna, H.; Juette, E.; Karastergiou, A.; Kondratiev, V. I.; Koopmans, L. V E; Kuniyoshi, M.; Kuper, G.; Van Leeuwen, J.; Maat, P.; Mann, R. G.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; Mulcahy, D. D.; Munk, H.; Nelles, A.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pietka, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Rottgering, H. J. A.; Rowlinson, A.; Scaife, A. M M; Serylak, M.; Shulevski, Alexander; Sluman, J.; Smirnov, O.; Steinmetz, M.; Stewart, A. J.; Swinbank, J.; Tagger, M.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; Vocks, C.; Van Weeren, R. J.; Wucknitz, O.; Yatawatta, S.; Zarka, P. (2016-12-01)
      The low-frequency radio spectra of the hotspots within powerful radio galaxies can provide valuable information about the physical processes operating at the site of the jet termination. These processes are responsible for ...

    • Lofar low-band antenna observations of the 3C 295 and boötes fields : Source counts and ultra-steep spectrum sources 

      Van Weeren, R. J.; Williams, W. L.; Tasse, C.; Röttgering, H. J.A.; Rafferty, D. A.; Van Der Tol, S.; Heald, G.; White, G. J.; Shulevski, A.; Best, P.; Intema, H. T.; Bhatnagar, S.; Reich, W.; Steinmetz, M.; Van Velzen, S.; Enßlin, T. A.; Prandoni, I.; De Gasperin, F.; Jamrozy, M.; Brunetti, G.; Jarvis, M. J.; McKean, J. P.; Wise, M. W.; Ferrari, C.; Harwood, J.; Oonk, J. B.R.; Hoeft, M.; Kunert-Bajraszewska, M.; Horellou, C.; Wucknitz, O.; Bonafede, A.; Mohan, N. R.; Scaife, A. M.M.; Klöckner, H. R.; Van Bemmel, I. M.; Merloni, A.; Chyzy, K. T.; Engels, D.; Falcke, H.; Pandey-Pommier, M.; Alexov, A.; Anderson, J.; Avruch, I. M.; Beck, R.; Bell, M. E.; Bentum, M. J.; Bernardi, G.; Breitling, F.; Broderick, J.; De Vos, M. (2014-10-01)
      We present Low Frequency Array (LOFAR) Low Band observations of the Boötes and 3C 295 fields. Our images made at 34, 46, and 62 MHz reach noise levels of 12, 8, and 5 mJy beam-1, making them the deepest images ever obtained ...

    • The LOFAR Multifrequency Snapshot Sky Survey (MSSS) : I. Survey description and first results 

      Heald, G. H.; Pizzo, R. F.; Orrú, E.; Breton, R. P.; Carbone, D.; Ferrari, C.; Hardcastle, M.J.; Jurusik, W.; Macario, G.; Mulcahy, D.; Rafferty, D.; Asgekar, A.; Brentjens, M.; Fallows, R. A.; Frieswijk, W.; Toribio, M. C.; Adebahr, B.; Arts, M.; Bell, M. R.; Bonafede, A.; Bray, J.; Broderick, J.; Cantwell, T.; Carroll, P.; Cendes, Y.; Clarke, A. O.; Croston, J. H.; Daiboo, S.; De Gasperin, F.; Gregson, J.; Harwood, J.; Hassall, T.; Heesen, V.; Horneffer, A.; van der Horst, A.J.; Iacobelli, M.; Jelić, V.; Jones, D.; Kant, D.; Kokotanekov, G.; Martin, P.; McKean, J. P.; Morabito, L. K.; Nikiel-Wroczyński, B.; Offringa, A.; Pandey, V. N.; Pandey-Pommier, M.; Pietka, M.; Pratley, L.; Riseley, C.; Rowlinson, A.; Sabater, J.; Scaife, A. M. M.; Scheers, L. H. A.; Sendlinger, K.; Shulevski, A.; Sipior, M.; Sobey, C.; Stewart, A. J.; Stroe, A.; Swinbank, J.; Tasse, C.; Trüstedt, J.; Varenius, E.; Van Velzen, S.; Vilchez, N.; Van Weeren, R. J.; Wijnholds, S.; Williams, W. L.; de Bruyn, A. G.; Nijboer, R.; Wise, M.; Alexov, A.; Anderson, J.; Avruch, I. M.; Beck, R.; Bell, M. E.; Van Bemmel, I.; Bentum, M. J.; Bernardi, G.; Best, P.; Breitling, F.; Brouw, W. N.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Conway, J. E.; De Geus, E.; De Jong, A.; De Vos, M.; Deller, A.; Dettmar, R. J.; Duscha, S.; Eislöffel, J.; Engels, D.; Falcke, H.; Fender, R.; Garrett, M.A.; Grießmeier, J.; Gunst, A. W.; Hamaker, J. P.; Hessels, J. W. T.; Hoeft, M.; Hörandel, J.; Holties, H. A.; Intema, H.; Jackson, N. J.; Jütte, E.; Karastergiou, A.; Klijn, W. F. A.; Kondratiev, V. I.; Koopmans, L. V. E.; Kuniyoshi, M.; Kuper, G.; Law, C.; Van Leeuwen, J.; Loose, M.; Maat, P.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; Mevius, M.; Miller-Jones, J. C A; Morganti, R.; Munk, H.; Nelles, A.; Noordam, J. E.; Norden, M. J.; Paas, H.; Polatidis, A. G.; Reich, W.; Renting, A.; Röttgering, H.; Schoenmakers, A.; Schwarz, D.; Sluman, J.; Smirnov, O.; Stappers, B. W.; Steinmetz, M.; Tagger, M.; Tang, Y.; Ter Veen, S.; Thoudam, S.; Vermeulen, R.; Vocks, C.; Vogt, C.; Wijers, R.A.M.J.; Wucknitz, O.; Yatawatta, S.; Zarka, P. (2015-10-01)
      We present the Multifrequency Snapshot Sky Survey (MSSS), the first northern-sky Low Frequency Array (LOFAR) imaging survey. In this introductory paper, we first describe in detail the motivation and design of the survey. ...

    • The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release 

      Shimwell, T. W.; Röttgering, H. J. A.; Best, P. N.; Williams, W. L.; Dijkema, T. J.; Gasperin, F. de; Hardcastle, M. J.; Heald, G. H.; Hoang, D. N.; Horneffer, A.; Intema, H.; Mahony, E. K.; Mandal, S.; Mechev, A. P.; Morabito, L.; Oonk, J. B. R.; Rafferty, D.; Retana-Montenegro, E.; Sabater, J.; Tasse, C.; Weeren, R. J. van; Brüggen, M.; Brunetti, G.; Chyży, K. T.; Conway, J. E.; Haverkorn, M.; Jackson, N.; Jarvis, M. J.; McKean, J. P.; Miley, G. K.; Morganti, R.; White, G. J.; Wise, M. W.; Bemmel, I. M. van; Beck, R.; Brienza, M.; Bonafede, A.; Rivera, G. Calistro; Cassano, R.; Clarke, A. O.; Cseh, D.; Deller, A.; Drabent, A.; Driel, W. van; Engels, D.; Falcke, H.; Ferrari, C.; Fröhlich, S.; Garrett, M. A.; Harwood, J. J.; Heesen, V.; Hoeft, M.; Horellou, C.; Israel, F. P.; Kapińska, A. D.; Kunert-Bajraszewska, M.; McKay, D. J.; Mohan, N. R.; Orrú, E.; Pizzo, R. F.; Prandoni, I.; Schwarz, D. J.; Shulevski, A.; Sipior, M.; Smith, D. J. B.; Sridhar, S. S.; Steinmetz, M.; Stroe, A.; Varenius, E.; Werf, P. P. van der; Zensus, J. A.; Zwart, J. T. L. (2017-02-09)
      The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168 MHz imaging survey that will eventually cover the entire Northern sky. Each of the 3170 pointings will be observed for 8 hrs, which, at most declinations, is sufficient ...

    • The LOFAR window on star-forming galaxies and AGN - curved radio SEDs and IR-radio correlation at 0 < z < 2.5 

      Rivera, G. Calistro; Williams, W. L.; Hardcastle, M. J.; Duncan, K. J.; Röttgering, H.~J.~A.; Best, Philip N.; Brüggen, Marcus; Chyzy, K.T.; Conselice, C. J.; De Gasperin, Francesco; Engels, D.; Gürkan, G.; Intema, Huib T.; Jarvis, M. J.; Mahony, E. K.; Miley, G.K.; Morabito, L. K.; Prandoni, I.; Sabater, J.; Smith, D. J. B.; Tasse, C.; van der Werf, P.; White, Glenn J. (2017-08-11)
      We present a study of the low-frequency radio properties of star forming (SF) galaxies and active galactic nuclei (AGN) up to redshift $z=2.5$. The new spectral window probed by the Low Frequency Array (LOFAR) allows us ...

    • Spectral analysis of hot subluminous stars 

      Heber, U.; Edelmann, H.; Lemke, M.; Napiwotzki, R.; Engels, D. (Astronomical Society of the Pacific, 1999)
      Optical spectra of 40 sdOB stars drawn from the Palomar Green and the Hamburg-Schmidt surveys are presented (including three EC 14026 stars). Eight of which are spectroscopic binaries.

    • Spectral analysis of sdB Stars from the Hamburg Quasar Survey 

      Edelmann, H.; Heber, U.; Hagen, H.J.; Dreizler, S.; Napiwotzki, R.; Engels, D.; Lemke, M. (2003-03)

    • Sub-arcsecond imaging with the International LOFAR Telescope : I. Foundational calibration strategy and pipeline 

      Morabito, L. K.; Jackson, N. J.; Mooney, S.; Sweijen, F.; Badole, S.; Kukreti, P.; Venkattu, D.; Groeneveld, C.; Kappes, A.; Bonnassieux, E.; Drabent, A.; Iacobelli, M.; Croston, J. H.; Best, P. N.; Bondi, M.; Callingham, J. R.; Conway, J. E.; Deller, A. T.; Hardcastle, M. J.; McKean, J. P.; Miley, G. K.; Moldon, J.; Röttgering, H. J. A.; Tasse, C.; Shimwell, T. W.; Weeren, R. J. van; Anderson, J. M.; Asgekar, A.; Avruch, I. M.; Bemmel, I. M. van; Bentum, M. J.; Bonafede, A.; Brouw, W. N.; Butcher, H. R.; Ciardi, B.; Corstanje, A.; Coolen, A.; Damstra, S.; Gasperin, F. de; Duscha, S.; Eislöffel, J.; Engels, D.; Falcke, H.; Garrett, M. A.; Griessmeier, J.; Gunst, A. W.; Haarlem, M. P. van; Hoeft, M.; Horst, A. J. van der; Jütte, E.; Kadler, M.; Koopmans, L. V. E.; Krankowski, A.; Mann, G.; Nelles, A.; Oonk, J. B. R.; Orru, E.; Paas, H.; Pandey, V. N.; Pizzo, R. F.; Pandey-Pommier, M.; Reich, W.; Rothkaehl, H.; Ruiter, M.; Schwarz, D. J.; Shulevski, A.; Soida, M.; Tagger, M.; Vocks, C.; Wijers, R. A. M. J.; Wijnholds, S. J.; Wucknitz, O.; Zarka, P.; Zucca, P. (2022-02-28)
      The International LOFAR Telescope is an interferometer with stations spread across Europe. With baselines of up to ∼2000 km, LOFAR has the unique capability of achieving sub-arcsecond resolution at frequencies below 200 ...